PB1988: EXTRAMEDULLARY BLAST CRISIS PRESENTING AS INFILTRATIVE OPTIC NEURITIS: A TREATMENT DILEMMA
Authors: Nezille Joy Lina
Journal: HemaSphere (2023)

Topic: 8. Chronic myeloid leukemia - Clinical Background: Chronic Myelogenous Leukemia (CML) is characterized by anemia, extreme blood granulocytosis and granulocytic immaturity, basophilia, often thrombocytosis and splenomegaly. It usually present in three phases: chronic, accelerated and blast phase. These phases play a large part in the determining the choice of targeted treatment to be used upon diagnosis. In the era of tyrosine kinase inhibitors (TKI), prognosis, and outcomes of patients with CML are markedly improved. But when disease progressed to accelerated or blast phase, this usually carry a poor prognosis. In patients on blast phase a treatment combination of TKI with systemic chemotherapy followed by allogeneic hematopoietic stem cell transplantation is recommended. Aims: Extramedullary blast crisis is described as infiltration of leukemic cells in sites other than the bone marrow. Treatment is usually directed towards the expression of blasts in flow cytometric studies or histopathology results. This report aims to describe a rare case of extramedullary blast crisis without marrow involvement managed without the benefit of knowing the lineage of blastic infiltration. Methods: A 30-year-old male diagnosed with Chronic Myeloid Leukemia on Imatinib 400mg/day presented with progressive bilateral vision loss and photophobia. Magnetic Resonance Imaging revealed retinal detachment with evidence of leukemic infiltrative optic neuritis. Flow cytometric studies was sent and no blasts were detected on both bone marrow aspirate and cerebrospinal fluid. Results: Our patient presented with progressive bilateral vision loss, in a background of a diagnosed CML, infiltrative optic neuritis was considered. Imaging studies did not show enhancement of the optic nerve. CSF and BMA analysis were also negative. Establishing the lineage of the blast is fundamental in deciding the systemic chemotherapy regimen. The question of whether to subject the patient to intensive chemotherapy or give a treatment targeted to the only presentation of blast crisis was carefully considered. Intravitreal injection of methotrexate was also planned but was put on hold due to the risk of spread of leukemic cells into the intravitreal space. After careful planning and consultation with other services, a more conservative approach was chosen. The patient was given weekly intrathecal chemotherapy with Methotrexate and Cytarabine for 4 doses followed by radiotherapy for 12 sessions. Imatinib was shifted to a second-generation TKI, Dasatinib which has known CNS penetration. An allogeneic hematopoietic stem cell transplantation was advised but due to financial constraints, the patient was unable to comply. As of this writing, patient has marked improvement in visual acuity in the left eye from counting fingers to 20/25 but the right eye’s visual acuity progressed to light perception owing to findings of total retinal detachment. Summary/Conclusion: A rare clinical presentation of extramedullary blast crisis with infiltrative optic neuritis was presented along with therapeutic options in managing such cases. The decision not to give aggressive chemotherapy on the merit that no evidence of lineage to guide us in choosing the most appropriate chemotherapeutic options is justifiable in our case. The option to give intrathecal chemotherapy, radiotherapy, and continuous tyrosine kinase inhibitor gave the patient an option to improve his vision and control his CML. To note, the rarity of the case makes the clinician aware that despite a more advanced phase of CML, patients can still be given a less toxic therapeutic approach that can help address the extramedullary blast crisis and still results in acceptable outcomes.Keywords: Chronic myeloid leukemia, Tyrosine kinase inhibitor